Oenocarpus distichus presents economic, ecological, and dietary potential for pulp market processed in natura. Germplasm conservation and genetic improvement depend on genetic divergence studies. The objective was to quantify genetic divergence in a native population of O. distichus genotypes based on fruit biometrics. The fruit length and width, fruit mass, pulp and seed, pulp and almond thickness, and pulp yield per fruit were evaluated. All fruit biometric characteristics of O. distichus palms show genetic variability. Genetic variations among genotypes are essential for predicting heredity and heterosis, which are essential for improving O. distichus production. Pulp yield and seed mass were negatively correlated. Almond thickness and pulp, seed mass and transverse diameter were positively correlated. Genetic distances between pair of genotypes ranged from 0.07 to 48.10 with three genetically distinct groups. The seed mass, almond thickness and transverse diameter contributed to genetic divergence. Heritability estimates the genetic control that can be obtained from O. distichus germplasm. Correlations between the variable pair reduce the evaluation effort and the resources to measure the genotype allocations in heterogeneous groups presenting high genetic variability. This makes it possible to select individuals for hybridization programs with F1 generation gains. Correlation and relative contribution networks, based on relationships graphical between fruit biometric characteristics, allow the variables selection with less effort and fewer measurements. O. distichus fruit biometric characters are efficient to quantify genetic divergence between genotypes.

This paper presents results from a study into the stability and adaptability of Eucalyptus multi-species hybrids in the state of Rio Grande do Sul, Brazil, using an index that includes volume growth and Pilodyn penetration. Clonal tests were established with 146 Eucalyptus clones from 34 different species and/or hybrids, in a randomised block design with 30 replications, and one plant per plot in four different sites. Diameter at breast height (dbh), tree total height (th), and Pilodyn penetration for indirect estimate of basic density were measured in trees at three years of age. An index (MAI_weight) combining mean annual volume increment and Pilodyn penetration was calculated. In the analysis of MAI_weight for each site, the best clones were from pure species (E. urophylla, E. grandis and E. saligna). In contrast, the evaluation of adaptability and stability between the four environments simultaneously showed that three-way cross and single cross hybrids ranked more highly: E. urophylla × (E. camaldulensis × E. grandis), E. grandis × (E. urophylla × E. grandis) and E. grandis × E. urophylla. This study demonstrates the importance of heterosis (hybrid vigour) to improving adaptability and stability. Genetic complementarity from crosses between different species was the principal process that produced the observed heterosis. While the pure species performed well in specific environments, the hybrids presented better broad adaptation to a range of environments. Breeding efforts should therefore account for these features when planning crosses and choosing sites for establishing trials.